The best book that I found for MTS and Visual Basic is "Professional Visual Basic 6 MTS Programming". It is published by Wrox in the VB COM series. It is written by Matthew Bortniker with James Conrad. You can click here to get specific information:
I had a problem with my application that I could not find an answer to for a long time. I finally contacted Microsoft's support line (for a fee of course) and the MTS expert was able to help me. I complained to him that there is no real good documentation on MTS and I was wondering where he was getting his information from. He said that this book is the best that he found and he uses it all the time.
Matthew Bortniker, as most Wrox authors that I found, has a wonderful sense of humor that makes the book easy to read.
If you use and/or develop MTS components, this book is a must have.